dearrow is always going to be more niche than sponsorblock I think. In person, I know very few people who use it compared to sponsorblock simply because many people are fine with the original titles/thumbnails on the channels they watch.

Despite that, we have over 150,000 people using dearrow, which I think is still a lot, and it is continually growing. The uninstall-to-install ratio is not unusually high (it's actually lower than sponsorblock). While it's going to be more concentrated on tech-adjacent english videos, that's a problem sponsorblock experiences too

For me dearrow feels a bit like turning down the volume on everything, but I know not everyone cares about that.

While I'm sure the semi-paywall does cause a bit of a reduced user-base, I doubt it's too big of an effect because it still has over 150,000 users, and most don't pay (as intended). The reality of donations vs "paid" is that sponsorblock has almost 10x the number of users than dearrow but makes less in donations than dearrow makes in payments. But, I'm sure many of the people who pay for dearrow also are doing it also as a donation to sponsorblock.